Lubrication system of internalcombustion engines



y 15, 1941- F. M. OWNER 2,249,155

LUBRICATION SYSTEM QF'INTERNAL-COMBUSTION ENGINES Filed Nov. 2l, 1939 aSheets-Sheet 1 July 15, 1941. F. M. OWNER 2,249,165

LUBRICATION SYSTEM OF INTERNAL-COMBUSTION ENGINES Filed NOV. 21, 1939 5Sheets-Sheet 2 53 Z2 1 u uuu 1%); moww v Patented July 15, 1941LUBRICATION SYSTEM OF INTERNAL- COMBUSTION ENGINES Frank Morgan Owner,Bristol, England, assignor to The Bristol Aeroplane Company Limited,

Bristol, England, a British company Application November 21, 1939,Serial No. 305,536 In Great Britain December 22, 1938 3 Claims. (Cl.123-496) This invention relates to the lubrication sys tems ofinternal-combustion engines,

It is usual to supply oil to the parts requiring lubrication by means ofan engine-driven pump of which the discharge conduit communicates with apressure-relief valve the function of which is to keep down to apredetermined value the pressure of the oil in the conduit. When theengine is started up from cold, particularly in cold climaticconditions, the high viscosity of the oil in the conduit makes anincreased pressure necessary; but the pressure must be controlled,otherwise there is a risk of damage to the pump and other parts of thesystem. l

The object of this invention isto ensure that, when the engine isstarted from cold, an adequate quantity of oil is supplied to the partsrequiring it and, at the same time, to prevent the pressure in theconduit from reaching a dangerously high value.

According to the invention, the lubrication system of aninternal-combustion engine .comprises, in combination, an engine-drivenpump, a conduit leading from the discharge sidelof the pump to the.parts requiring lubrication, and means directly responsive to thetemperature of the oil, or, of the engine, and operative. to maintainthe pressure in the said conduit at one predetermined maximum when theengine is running at its normal temperature and at .a higherpredetermined maximumwhen the engine is cold.

The. said conduit preferably communicates with two pressure-reliefvalves, one of which (the normal-pressure valve) is normally, operativeto keep downthe pressure in the conduit to a value sufficient for normalrunning condi-- tions and the otherofiwhich (the high-pressure valve) isoperativeto prevent the pressure in the conduit fromexceeding a valuesubstantially higher than the normal pressure. The saidtemperature-responsive means renders the normal-pressure valveinoperative when the engine is cold, so that the'oil in the conduit isat the higher pressure permitted-by the high-pressure.

whereby the high-pressure valvebecomes inoperative.

It is to be understood that the oil is supplied to the parts requiringlubrication along the same conduit; whichevervalve is in operation, No

separate conduit-is required for the. supply of oil at the higherpressure. A

The temperature-responsive means may render the normal-pressure valveinoperative by ad-,

mitting the-pressure oilto both sides of it or by closing its dischargeport.

A specific embodiment of.

ing to the invention,

Figure 2 shows the-arrangementotthe mal-pressure valve and thetemperature-respom.

sive means, and

Figure 3 is an enlarged of Figure 2.

As shown in Figure 1, a radial-cylinder aircraft engine having acrank-case l0, crank-shaft ll,

cylinders l2, oil-sump l3 and accessories 14;

drives-two oil-pumps l5, 16 of the intermeshing gear-wheel type, thepumps and other parts of; the hydraulic circuit being showndiagrammatically to-a greatly enlarged scale in relation to the size ofthe, engine. The, pump l5 (termed asupply of pressure liquid. The usedlubricating oil is drained from the engine crank-case into; the sump I3fromwhich it is sucked by the pump it (termed the fscavenge pump), thispump're-' turning the oil through a suitablecooler (not shown) tothetank l'l. V p 7 The pressure-pump l5 and scavenge pump I6 areconvenientlymountedin.the same casing, in"

the usual way, and driven by thesame shaft.

In the conduit l8 leading from the pressur'epumpto the engine there is abranchconduit 2|] which leadsrto the valve-chest H of a slide valve 22which, inthe preferred form of the" invention illustrated, is a,piston-valve'having lands 23, 24 and an operating rod 25; Thechest 2|is formed with ports 26, 21 through which theoil can normallygainraccess to the raceo'f "a valve 28 (the normalepressurevalve)'whi'ch 'i s slidable in a cylinder 29 ,which contains a com pressionspring 30 tending to hold the valve '28 in the position shown in whichadateral'; is closed by thev skirt of .thevalve. f;

the invention will now be described, by way of example,,witli referenceto the accompanying drawings of which- Figure 1 is a diagram showing the,hydraulic' circuit of an internal-combustion engine accord view' or thee d a e A conduit 32 leading from the tank H to the intake of thepressure-pump I5 is enlarged to form a chamber 33 containing a capsule34 containing fluid having a suitable coefi'icient of expansion. Thecapsule is anchored at its righthand end so that the changes in thetemperature of the .oil in the chamber 33 produce endwise movements ofthe free left-hand end and therefore of the rod 25. When the engine andoil are at their normal working temperature, the capsule 34 is expandedso that the rod and piston-valve 22 occupy their extreme left-handposition as shown. In this position of-the pistonvalve the land 24isolates aport 3-5 in the valvechest 2| from oil entering the port :26.strength of the spring 36 in. relationto the area of the exposed face ofthe normal-pressure valve 28 is so chosen that the valve lifts againstthe force of the spring when the oil pressure, in the conduit20 exceeds80 lbs per square inch, and

uncovers the port 3| whereby the pressure, oil is discharged alongv aconduit 36 and returned. to the/conduit 32. onthe intake side of; thepressurepump. .At. a point. beyond the maximum movement of the valve 28,the valve-cylinder 29 is formedwith anotherport 31 which is connectedbya conduit 38..to theport already referred to. :Also theconduit '36 .isconnected by a short branch..89 totheinterior of the valve-chest2l onthe right-hand side of the land.'24.

When the engine is being started up from cold, the capsule 34 iscollapsed so that the valvei22 is.in aposition in which the land 24 liesto the right of the port'35. Consequentlythe pressure of the oil in theconduit 20pis exerted not only on the face of the valve 23 through theports. 26 and.2| but also on the back of the; valve through the. port35, the conduit'38 and the port 31. .Consequently, the only unbalancedforce actingruponlthe-valve 28 is the pressure ofthe spring30so.that,,however much'the oil pressure may. rise,.Ithe valve 28remains-closed andjthe pressureistherefore notrelieved.

Another branch-pipe 39 leads from theconduit -|8 to a ball-valve 46.(the high-pressure valve-abovereferredto) which is normally held omitsseatby. a strongspringM reacting'against theeother. end-42 of the valvechamber. The strength oithespringjlin relation to the area ofthe-ball issuch that-the valve lll-is lifted from .-its-seatwhen the oil pressureofthe oil ,in the'branch ,39. exceeds, 20.0 lbshper square inch. Thevalve then lifts andthe pressure is relieved througha ,bran=ch.43 to theconduit 4.4 leading from the: sump. |-3 to the intakeof the scavengepump-l6. The oilpressureinthe system is thus prevented by the valve fromexceeding a certain maximum (such as 200 lbs..per square inch) andcirculation of the ,oil, at this pressure continues. until thetemperatureof the engine and the'oil rises. to the. normalworking.temperature. When= therequired working temperature is=-r,eached, the capsule -34 expands, moves the valve- 22 to "theposition shown .in .Figure v1 whereby the-port-35is isolated fromthe oilin the condu-it 20; the normahpressure valve 28 thus becomes operativeto prevent. theoil. pressure from exceeding thenormal. pressure (forexample,y-80 l-bs; perss uare inch) iItfwi-lltbe' seen'from theabovedescrintion that the temperature-responsive. vmeans .34-.rendersthe normahpressureva1ve28 inoperative when the engine is coldso thatetheoil in the conduit I8 is at the higher. pressure permittedhy thehigh-pressure valve 40. Whether the oil is be- The 1'.

ing delivered at the normal pressure or at the higher pressure, it issupplied to the engine along the conduit l8, no separate conduit beingrequired for the supply of oil at the higher pressure.

It will be understood that Figure 1 is purely diagrammatic; thepreferred construction of the normal-pressure valve, piston-valve, andassociated parts will now be described with reference to Figures 2 and3. The pressure-pump (not shown in Figure 2) takes in oil from a chamber'33-and delivers it under pressure to a chamber 45. The chamber 33 isclosed by a diaphragm 46 into'which the stem 41 of the temperature-.-responsive capsule 34 is screw-threaded, being secured inany desiredposition of adjustment by a'lock-nut 48. The parts 4'! and 48 arecovered in by means of a screw-threaded 'cap 49. The capsule 34 is thusanchored at its righthand end; its left-hand end carries a trans-'versely slotted member50 to engage the head 5| of the piston-valve .22(see Figure 3) The valve 22 slides in a fixed sleeve 2| which is locatedin suitable. holes in the pump-casing 52 and which controls a passage 53leading from thepress-ure-chamber 45 to the normal-pressure valve whichwill now be described. 7

The casing 52,is formed with a tubular extension 54 into which isscrew-threaded a tube 55. The tube 55 contains a compressiontspring 56engaging at one endwith an adjustable abutmentr 51. and at the other endwith the interior of the cup-shaped normal-pressure valve .58. The-valve58 slides ina ported sleeve 59 having a flanged end 66 against which thevalve normally abuts, and radial ports 6| communicating with a passage62 in the surrounding casing 54. The passage .62 communicates, by apassage shown diagrammatically at 63, with theintakechamber 33 ofthe,pressure pump. Theouter end. of the. sleeve is surrounded by anotherchamber 64 which communicates with the interior of the .valve 58 througha space 65, and

through the oblique conduit 66 with an external groove 61. cut. in thevalve-sleeve. 2

The parts- 59, .58, 56 of Figure 2 correspond respectively with.theparts 29, 26. and3|l .oLEi urel. The ports- 6|, of Figure 2correspond .to the ports shown diagrammatically as 3| in Figurell andtheconduit-GG.ofFigure 2. corresponds to the'conduit .33 of Figure 1.The preferred form-of-thepiston-valvelZis shown in Figure 3. The lands23and.24 are. separated by.a.portion of somewhat reduced. diameter .68 andthe stemcf the valve is drilled from .end to end with av bore 69. whichcommunicates with the intakerchamber 33 through transverse ports .10formednear the right-hand end of the stem. The sleeve 2| is formed withthe ports 26 and 21 in the manner already described with reference toFigural and, in addition, is cut with radial ports II which connect thegroove 61, and therefore the conduit 66, either to the ports 26 and 21,when the engine is cold, or to'the space on the right-hand side of theland 24, when the engine is hot. The ports correspond to the port 35 inFigure 1.

The purpose of the passages 69 and 19'is 'to prevent the development ofhigh pressure or vacuum in the left-hand end'of the valve-sleeve 2| suchas would interfere with the free m'ove ment-of the piston-valve 22. Thecommunication' between the inside of the valve-sleeve and the intake-camber 33 'is illustrated -diag'ram-' matically in Figure 1 by the pipes88, 36 and 32' but it is unnecessary to provide the physical counterpartof the pipe 89 in the particular construction described with referenceto Figures 2 and 3 since, as will be seen, the right-hand end of thesleeve 2| opens directly intothe chamber 33.

The valve 22 is shown in Figure 2 in the position in which the capsule34 is fully expanded as the result of the high temperature of the oil.The valve therefore isolates the ports II from the ports 28 and 21whereby the normal-pressure valve 58 is operative to relieve the oilpressure in the chamber 45 when it tends to exceed the normal pressureof, say, 80 lbs. per square inch. Any rise in the pressure depresses thevalve 58 as shown in Figure 2 whereby oil is returned through t echamber 62 and conduit 63 to the intake-chamber 33. On the other hand,Figure 3 shows the valve 22 in the position it occupies when the engineis cold and the capsule 34 collapsed. In this position the back of thenormal-pressure valve 58 is subjected through the ports 1! and conduit86 to the same pressure as the face of the valve. The valve is thereforeheld closed by the spring 56 in the manner already described withreference toFigure 1.

The collapsible capsule 34 is preferably spring-biased towards theposition shown in Figure 2 so that, in the event of failure of the capsule, the lubrication system would operate at running conditions and theother of which is operative to prevent the pressure in the conduit fromexceeding a value substantially higher than the normal pressure, andmeans directly responsive to the temperature of the oil and operative torender the normal-pressure valve inoperative when the engine is cold sothat the oil in the conduit is at the higher pressure permitted by thehigh-pressure valve.

2. A lubrication system for an internal-combustion engine comprising, incombination, an engine-driven pump, a conduit leading from the dischargeside of the pump to the parts requiring lubrication, two pressure-reliefvalves communicating with said conduit, one of which is normallyoperative to keep down the pressure in the conduit to a value sufficientfor normal running conditions and the other of which is operative toprevent the pressure in the conduit from exceeding a value substantiallyhigher than the normal pressure, and'means directly responsive to thetemperature of the 'oil to admit the pressure oil to both sides of thenormal-pressure valve when the engine is cold so' as to render thenormal-pressure valve inoperative.

3. A lubrication system for an internal-combustion engine comprising, incombination, an engine-driven pump, a conduit leading from the dischargeside of the pump to the parts requiring lubrication, two pressure-reliefvalves communicating with said conduit, one'oi which is normallyoperative to keep down the pressure in the conduit to a value sufficientfor normal running conditions and the other of which is operative toprevent the pressure in the conduit from exceeding a value substantiallyhigher than the normal pressure, a slide valve operative to

